HOUSTON -

Houston firefighters were busy Thursday morning battling a massive blaze that ripped through a northwest Houston warehouse.

The fire broke out at the business in the 11000 block of West Little York around 5:30 a.m. A passing motorist spotted the flames and called 911.

When firefighters arrived, the flames were so intense they had to call in additional crews for help.

“First units found heavy smoke coming from the building they called for a second alarm for manpower,” said Robert Rasa, Cy-Fair Volunteer Fire Department.  “The fire looks like it started in the middle of the building. There’s a lot of smoke and heat damage to most of the building,” Rasa said.

Five agencies worked together.  Heat was a factor for the firefighters as well as water supply.

“We added tankers to the call knowing we don’t have hydrants in the area,” Rasa said.

The fire was knocked out quickly.

Several businesses operate out of the facility. The part that caught fire was a business that manufactures diapers.

“The air quality is still not safe for us to get in there so the fire department is working on getting the building ventilated so we can get investigators inside safely to see what caused the fire,” said Lt. Dean Hensley, Harris County Fire Marshal's Office.

Firefighters had to return to the scene shortly after leaving because a few hot spots flared up.